In a dramatic step on Wednesday, Rabbi Yonah Metzger has urged Israel and world rabbis to collectivelyshun the members of the Orthodox sect Neturei Kartaand ban them from entering any temples.

Metzger said he was disgusted that rabbis from the sect —which is anti-Zionist and doesn'tbelieve the state of Israel should exist —participated in the conference held Monday and Tuesday in Tehran.

Itattracted some of the world's most prominent anti-Semites and Holocaust deniers, including former Ku Klux Klan leader David Duke.

Duke and others,described by organizers as "scholars," presented research that called into question details of the Nazi slaughter ofsix million Jews during the Second World War — or whether it happened at all.

"This is a crime against the people of Israel," Metzger said. "To deny the most sensitive issue in Jewish history, and to co-operate with the Hitler of our day? One of those men introduced himself as the chief rabbi of Austria — and he's not even a rabbi."

Iranian President Mahmoud Ahmadinejad, who has referred to the Holocaust as a "myth" and remarked that Israel should be "wiped off the map," initiated the conference.

A spokesman for the Neturei Karta said he accepts the Holocaust as a fact, but defended speakers who question the scale of the genocide.

"Even in the time of Hitler, there are ways in which the Jewish people have to deal with non-Jews, and if you do it our way, then it helps to save lives and ensures there won't be a Holocaust," Hillel Deutsch said.

"That's why we told President Ahmadinejad that we liked and admired him."

A bearded delegation from Jews United Against Zionism, including members from Jerusalem, also attended the conference and expressed interest in ideas brought up there. Photos of the group at the event outraged many Israelis.

Neturei Karta leaders said they were aware of Metzger's calls to ban them from praying with fellow Jews in synagogues.

Only a court with a panel of at least three rabbinical judges has the power to start a boycott, according to Jewish law. Metzger's spokesman told the Ynet Israeli news site that the rabbi has "made the call on his own without other rabbis."